The present disclosure relates to techniques to increase and/or optimize reservoir production, and more particularity, to selection of geological zones for landing horizontal wellbores for subsequent hydraulic fracturing. The present disclosure relates to core characterization, and the evaluation of rock layering and interface properties on hydraulic fracture growth and connectivity. The present disclosure relates to the evaluation of production potential from fracturing rocks with complex fabric. The present disclosure relates to selecting landing locations based on an evaluation of potential fracture segmentation and maximizing fracture connectivity for optimal well production.
Various methods have been proposed for optimal selection of horizontal wellbore trajectories. These various methods are primarily based on geometrical considerations of the wellbore trajectory, on the evaluation of bulk reservoir and mechanical rock properties, or on both geometrical considerations and the evaluation of bulk reservoir and mechanical rock properties. The methods based on geometrical considerations of the wellbore trajectory emphasize problems and opportunities of having wellbores with complex trajectories. It is generally widely accepted that complex trajectories result in complex pathways for production, create traps for liquid loading and are, in general, detrimental to hydrocarbon production. When possible, it is thus preferable to have simple, linear, well paths. The methods based on the evaluation of bulk reservoir and mechanical rock properties emphasize criteria based on the quality of the reservoir, which could be evaluated via a single property (e.g., highest porosity, highest permeability, highest Gamma Ray radiation level), or a combination of these properties.
Methods for lateral placement and completion design have also been proposed based on completion quality (e.g., minimum stress, brittleness, presence of fractures), or a combination of completion quality considerations and reservoir quality. For example, at the time of writing in 2015, service providers are currently using a combination of well trajectory control, to place the wellbore in the zone with best reservoir quality, and using log- or drill cuttings-derived properties to place perforation stages in regions with uniform stress (as predicted along the wellbore).
In general these methods for lateral placement and completion design are based on well log measurements or seismic data. Some methods use statistical analysis of properties measured on logs, or properties evaluated at grid cells on 3D earth models, to calculate their criterion for lateral landing.
There is no known method that proposes landing laterals based on the presence and distribution of weak interfaces and thin rock layering on reservoirs with complex fabric. There is no known method that focuses on rock weak planes, pinch-out points, or thin rock layering, and utilizes geologic, petro-physical properties measured on cores, to understand fracturing behavior in reservoirs with complex fabric, and the effect of the complex fabric on hydraulic fracture growth. There is currently no other method that takes into consideration interfaces and thin layering to evaluate production potential and landing locations.
Because the thickness of thin interfaces may range from a few millimeters to a few centimeters, these thin interfaces may be difficult to detect using standard resolution open hole logs, and are not part of any conventional method of evaluation. The same detection difficulty occurs in the reservoirs with thin rock layering.